My research focus is biomimetic materials based on poly-N-substituted glycine (peptoid) constructs for use in biomedical applications. Current research projects include peptoid-based affinity reagents (affitoids) and surface coatings for antibody microarrays.

Affitoids: While researchers are discovering many potential biomarkers for early stage cancer, validating these biomarkers for use in diagnostic systems is becoming increasingly difficult. The standard technique for validation is enzyme-linked immunosorbent assay, which requires two good affinity reagents against the biomarker. There are a limited number of affinity reagents currently available and the techniques for affinity reagent development are slow and expensive, greatly limiting the validation of biomarkers. Synthetic affinity reagents, such as affitoids, have the potential to be screened for much more rapidly than is currently possible. The rapid discovery of affinity reagents will ultimately lead to rapid validation of early stage breast cancer biomarkers, and thus a quicker path to a clinical diagnostic for early stage breast cancer.

Peptoids are ideal candidates for use as an affinity reagent due to their inexpensive and facile synthesis, ability to incorporate unique reactive sites, highly stable helical structures, and potential for non-biofouling design. A peptoid designed for stability and with included reactive sites will serve as the support for an affinity reagent, essentially mimicking the constant region of an antibody. Reactive sites on the surface of the peptoid will be used to incorporate antigen binding peptides/peptoids.

Peptoid-Based Surface Coatings: The complex chemical make-up of proteins can lead to structural instability when immobilized on a solid surface, and thus there is a potential for antibodies to unfold and lose functionality in the microarray format. While a number of different slides with a variety of surface modifications and chemistries are available commercially and many researchers investigating novel substrates, the optimal slide chemistry for the immobilization of antibodies has not yet been determined.

Peptoids are easy and inexpensive to synthesize using an automatic peptide synthesizer, and can be designed to form extremely stable secondary structures. In addition, previous studies have shown that properly designed peptoids create a robust surface coating that resists the attachment of proteins and cellular debris. In addition, recent unpublished studies by Dr. Annelise Barron’s research group (Stanford University) have shown that when dried on a flat surface, helical peptoids form microstructures. These structures take on various forms, such as micropores and microspheres, depending on side chain chemistry and the solvent. A coating that incorporates the various attributes of peptoids would be ideal for microarrays, as it would (i) allow for increased surface area for antibody immobilization, (ii) create a barrier between the glass slide and the antibody to retain function, (iii) be easy and inexpensive to synthesize, and (iv) minimize the background signal due to non-specific protein binding.